The present invention relates to a power-source control apparatus for a vehicle which is equipped with a regenerative generator conducting deceleration regeneration, and in particular to a power-source control apparatus for a vehicle which can provide a stable power supply even when a load of electric devices is high.
Recent years, a vehicle which has a function of regenerating deceleration energy at the time of deceleration of the vehicle and utilizing the regenerated energy as a power supply to electric devices, in addition to improving combustion of an engine, reducing vehicle weight, and so on, in order to improve the fuel efficiency (gas mileage) has been put to practical use.
US Patent Application Publication No. 2006/0097577 A1, for example, discloses a vehicle power supply system which comprises a main power source for power supply to a starter and general electric devices, which is comprised of a normal battery, an auxiliary power source for a regenerative power storage to store power generated by an alternator, which is comprised of a Li (Lithium) ion battery, and a DC/DC convertor and a switch which are provided between the main power source and the auxiliary power source to control power charge/discharge.
In the system described above, however, since the battery of the main power source may deteriorate through its frequent charge/discharge, it may be necessary that the charge of the battery is restricted and a burden of the auxiliary power source is increased. Further, there is a problem in that if the amount of power storage of the auxiliary power source is small, a sufficient amount of power may not be supplied to the electric devices.
Accordingly, it is considered that a capacitor having a high capacity with a relatively high storage voltage (25 V) is used as a regenerative power storage means which does not improperly deteriorate through its frequent charge/discharge, but has a sufficient power-storage amount.
However, in a case in which the above-described capacitor having the high capacity is used, even when the load of the electric devises is high and the output of the capacitor is sufficient, if a capacity (output current) of the DC/DC convertor provided between the electric devices and the capacitor is short, the sufficient power may not be supplied to the electric devices. Accordingly, it may be necessary that the capacity of the DC/DC convertor is made higher according to the maximum electric load of the electric devices. This may cause problems of a cost increase as well as a large size.
Herein, it may be considered that the power supply from the battery is additionally conducted in order to supply the sufficient power to the electric devices, restraining the capacity of the DC/DC convertor. However, if a remaining capacity of the battery becomes too low, that is—the battery is excessively discharged, there is a concern that problems of the battery being dead or the battery's deterioration may occur.